1. Field of the Invention
The present invention relates generally to a photographing system, and more particularly to an improvement in a photographing time setting method that is carried out by a photographing apparatus.
2. Description of the Related Art
In the field of biological chemistry and molecular biology, a fluorescence detecting system using a fluorescent dye as a labeling material is hitherto known. According to this system, the evaluations or the like of the arrangement of a gene, the expression level of a gene, the path and state of the metabolism, absorption, and excretion of applied matter in a laboratory mouse, and the separation, identification, molecular weight, and characteristics of protein can be performed, by reading out image information related to a sample distributing a specific organism-originated matter labeled with a fluorescent dye.
For example, by utilizing electrophoresis which moves a living cell in suspension or a biological compound (protein, etc.) in a solution to a positive or negative electrode through an electric field as a result of electric charge, a plurality of deoxyribonucleic acid (DNA) fragments are electrophoresed on a gel support body, after a fluorescent dye has been added into a solution containing the plurality of DNA fragments. Or a plurality of DNA fragments are electrophoresed on a gel support body containing a fluorescent dye. Alternatively, after a plurality of DNA fragments have been electrophoresed on a gel support body, this gel support body is immersed into a solution containing a fluorescent dye. In this way, a gel support body (sample) distributing specific DNA fragments (organism-originated matter) labeled with fluorescence is obtained. Within a black box shielded from external light, the obtained gel support body placed on a suitable sample tray is irradiated with exciting light which excites the fluorescent dye employed as a labeling material. The fluorescence emitted from the gel support body is photoelectrically read out by photoelectric read means through a lens. In this way, image information representing a distribution of DNA fragments labeled with fluorescence is acquired, and based on the acquired image information, a visual image is displayed on a display section such as a CRT display, whereby the evaluation of the molecular weight of the DNA fragment and the like can be performed.
In the same field, on the other hand, a chemiluminescence method of photographing the image of chemiluminescence by employing photoelectric read means such as a charged-couple device (CCD) is known as a method of detecting a nucleic acid and protein in a membrane filter or the like after blotching. As an apparatus for photographing such an image of chemiluminescence, a photographing apparatus is known in which, as with the above-mentioned fluorescence detecting apparatus, a membrane filter or the like is placed on a suitable sample tray and housed within a black box shielded from external light. Within this black box, chemiluminescence emitted from the membrane filter or the like is photoelectrically read out by photoelectric read means through a lens, and in this way, image information representing a distribution of specific protein or the like reacting to a predetermined luminescent chemical substance is acquired.
Here, the above-mentioned photographing apparatus with the object of detecting chemiluminescence can also be used as a photographing apparatus for the aforementioned fluorescence detecting system, by further providing an exciting light source for exciting a fluorescent dye and an exciting-light cut filter for permitting only the incidence of fluorescence on the photoelectric read means and preventing the incidence of exciting light. Therefore, a photographing apparatus adding the function of detecting fluorescence to the photographing apparatus for chemiluminescence detection has been developed.
That is, in the case of performing photographing for chemiluminescence detection, exciting light is prevented from being emitted. Also, the exciting-light cut filter is removed from the optical path of chemiluminescence, and chemiluminescence emitted from a sample is detected by the photoelectric read means. In the case of performing photographing for fluorescence detection, on the other hand, a sample is illuminated with exciting light. The exciting-light cut filter is disposed in the optical path of the fluorescent emitted from the sample, and the light source and the exciting-light cut filter are switched separately or integrally such that fluorescence alone is detected by the photoelectric read means. Moreover, in the case where there is a great difference in intensity between fluorescence and chemiluminescence, the quantity of light to be incident on the photoelectric read means is adjusted by providing a variable diaphragm.
Furthermore, the aforementioned photographing apparatus can also be used as a digitizer, in which a translucent manuscript (film, etc.) or a reflecting manuscript (a photograph, etc.) is irradiated with illuminating light and the transmitted image or the reflected image is photoelectrically read out by photoelectric read means through a lens in order to obtain a digital image. In this case, the light to be emitted from the exciting light source employs white light, not exciting light in a band that can excite fluorescence. Also, the quantity of the transmitted light or reflected light to be incident on the photoelectric read means is limited.
Furthermore, some of the aforementioned photographing apparatuses rendering switching of a photographing method possible in accordance with a photographing object are known as being capable of photographing an image suitable for the size of a sample by varying a viewing angle that is incident on photoelectric read means through a lens. That is, in the apparatus capable of photographing an image suitable to the size of a sample, a plurality of sample-tray disposing sections each having a different distance from the lens are formed so as to place a sample tray thereon. The sample tray can be placed selectively on one sample-tray disposing section of the plurality of sample-tray disposing sections. The lens is moved in the optical axis direction in accordance with the selected sample-tray disposing section, whereby focusing on the light-receiving surface of the photoelectric read means is rendered possible.
The exposure of the photoelectric read means employed in the above-mentioned photographing apparatus, incidentally, is controlled by a camera controller. If the operator inputs instructions to start exposure and end exposure, the camera controller will control the start and end of photoelectric reading that is performed by the photoelectric read means. Thus, the camera controller constitutes the photographing system along with the photographing apparatus.
There are cases where the photographing system includes analysis computers (including personal computers) that perform quantitative analysis and the like by applying various kinds of image processing to an image signal read out by the photoelectric read means.
In the above-mentioned photographing system, incidentally, the operator inputs instructions to start exposure and end exposure to the camera controller or the analysis computer. However, there is a problem that it is difficult to suitably set exposure time from the start of exposure to the end of exposure. Particularly, because fluorescence and chemiluminescence are very weak, there is a need to perform exposure for a long time to obtain a certain degree of light quantity when the light is employed in quantitative analysis. In addition, suitable exposure time varies between the case of fluorescence detection and the case of chemiluminescence detection and also varies depending on the kind of labeling fluorescent dye or the kind of labeling chemical substance. Generally, it is possible to set such suitable exposure time by experience. However, in the case where there is a difference in the density of a sample or the case where a new kind of fluorescent dye or the like is employed, the actual situation is that exposure time can be set only by trial and error.
On the other hand, it is conceivable that a photo detector is provided in the interior of a black box separately from the photoelectric read means and, based on a quantity of light detected by this photo detector, exposure time is set to the photoelectric read means. However, it is practically impossible to detect weak light, such as fluorescence and chemiluminescence, with higher sensitivity than the photoelectric read means. Thus, it is impossible to provide such a photo detector.
The present invention has been made in view of the aforementioned circumstances. Accordingly, it is an object of the present invention to provide a photographing system that is capable of photographing a sample with an exposure time suitable for the sample without relying on an operator""s experience.
To achieve this end, the photographing system according to the present invention performs temporary photographing for setting exposure time for actual photographing prior to the actual photographing for acquiring an image signal. Furthermore, the photographing system switches exposure time for the temporary photographing in accordance with a photographing method corresponding to the kind of sample to be photographed and/or the kind of light emitted from the sample.
That is, the photographing system of the present invention comprises a photographing apparatus, a camera controller, photographing-method input means, temporary exposure time setting means, and actual exposure time setting means. The photographing apparatus photographs light emitted from a sample as a two-dimensional image signal by photoelectric read means, the sample being provided within a black box shielded from light. The camera controller controls exposure time for photographing which is performed by the photoelectric read means. The photographing-method input means receives input of a photographing method corresponding to the kind of sample and/or the kind of light emitted from the sample. The temporary exposure time setting means stores a look-up table in which the kind of the photographing method is caused to correspond to temporary-photographing exposure time that is used to obtain proper actual-photographing exposure time, obtains the temporary-photographing exposure time in accordance with the kind of photographing method input from the photographing-method input means by making reference to the look-up table, and inputs the obtained temporary-photographing exposure time to the camera controller. The actual exposure time setting means sets actual-photographing exposure time, based on a temporary-photographing image signal obtained in temporary photographing controlled by the camera controller in accordance with the temporary-photographing exposure time and based on the temporary-photographing exposure time, and inputs the set actual-photographing exposure time in the camera controller.
The light emitted from the sample is, for example, fluorescence, chemiluminescence, illuminating light reflected from the sample, or illuminating light transmitted through the sample.
It is preferable that the aforementioned photoelectric read means employ an interline type CCD equipped with a cooling element, capable of having a wide dynamic range which can detect weak chemiluminescence and fluorescence with good linearity and also taking out a pseudo-dynamic image by reiteratively performing photoelectric reading in a short time. The present invention, however, is not to be limited to the interline type CCD. In the photoelectric read means employing the CCD, it is preferable that in the temporary photographing, the camera controller switch the CCD to photographing that is performed by a binning function. The reason for this is that by reading out a plurality of pixels as 1 pixel by means of the binning function, rapid reading can be realized, while ensuring a quantity of light per 1 pixel (in the case of a plurality of pixels handled as 1 pixel) to some degree.
The photographing method varies depending on the kind of sample to be photographed and/or the kind of light emitted from the sample. For instance, in the case of a sample (e.g., gel, etc.) distributing a specific organism-originated matter labeled with a fluorescent dye, the photographing method emits exciting light and disposes an exciting-light cut filter between the sample and the photoelectric read means so that the exciting light is not incident on the photoelectric read means. In the case of a sample (e.g., a membrane filter, etc.) distributing a specific organism-originated matter labeled with a chemical substance that emits chemiluminescence, the photographing method emits no exciting light and does not dispose the exciting-light cut filter between the sample and the photoelectric read means. Note that when light reflected from or transmitted through a sample (manuscript) is photographed, the photographing method emits illuminating light from the photoelectric read means side of the manuscript or from the opposite side of the manuscript from the photoelectric read means. In addition, when the light emitted from a sample is fluorescence, the photographing method is the same as the photographing method in the case of the above-mentioned sample distributing a specific organism-originated matter labeled with a fluorescent dye. Furthermore, when the light emitted from a sample is chemiluminescence, the photographing method is the same as the photographing method in the case of the above-mentioned sample distributing a specific organism-originated matter labeled with chemical substance.
In a preferred form of the present invention, the photographing system further includes display means for displaying the actual-photographing exposure time set by the actual exposure time setting means. One reason for this is that when the actual-photographing exposure time is set to a very long time, it becomes easy for an operator to determine whether actual photographing is in progress or the system has stopped due to a defect. Another reason is that because the set actual-photographing exposure time can be visually recognized, the operator does not need to be close to the photographing system until the end of actual photographing not knowing when the photographing will be finished, and therefore the display means is very useful in practical use.
The actual-photographing exposure time set by the actual exposure time setting means may have a fixed upper limit value. When the exposure time calculated by the actual exposure time setting means is over an excessively long time, the photographing system will be occupied for a long time by the sample. There are cases where, considering the attenuation of the quantity of light emitted from the sample, image signals with substantially little difference can be obtained between the case of such overexposure and the case where exposure is ended before that. In such a case, waste due to overexposure can be avoided. This is why the actual-photographing exposure time may have a fixed upper limit value.
The setting of the actual-photographing exposure time by the actual exposure time setting means may be performed based on part of the temporary-photographing image signal corresponding to part of the sample, obtained in accordance with the photographing method input to the photographing-method input means. The reason for this is as follows. There are cases where, depending on the kind of sample or the like, an area in the sample that emits light is limited to a fixed range. In such a case, it will be sufficient and desirable if actual-photographing exposure time is set only based on part of the temporary-photographing image signal corresponding to the fixed range.
The temporary exposure time setting means may have temporary-photographing exposure time input means for receiving input of temporary-photographing exposure time. When the temporary-photographing exposure time is input to the temporary-photographing exposure time input means, the temporary exposure time setting means may input the input temporary-photographing exposure time to the camera controller independently of the look-up table. The reason for this is that, when temporary photographing is desired in a changed temporary-photographing exposure time, it can easily be changed. In this case, the temporary exposure time setting means may rewrite the corresponding relationship set in the look-up table, based on the temporary-photographing exposure time input to the temporary-photographing exposure time input means and the photographing method input to the photographing-method input means. It is preferable that rewriting be performed in line with a statistical method. The xe2x80x9cin line with a statistical methodxe2x80x9d is intended to mean, for example, a method of selecting the average value of the temporary-photographing exposure times input to the temporary-photographing exposure time input means for each photographing method input to the photographing-method input means.
Furthermore, the temporary exposure time setting means may further be equipped with look-up table rewriting means for directly rewriting the look-up table itself. The reason for this is that the look-up table rewriting means can easily cope with the case where a new photographing method is developed, or the like.
Note that the camera controller may be constructed integrally with the photographing apparatus.
Also, the input of the photographing method to the photographing-method input means does not need to be performed by the operator. For example, the input may be performed by detecting the contents set in the photographing apparatus by the operator, specifically the selecting operation of the presence of emission of the exciting or illuminating light, the selecting operation of the direction of emission of the illuminating light, the operation of the exposure diaphragm, and the selecting operation of the presence of the exciting-light cut filter by sensors or the like, respectively, and by inputting these results of detection. The reason for this is that, based on the above-mentioned results of detection, the photographing method can be determined unequivocally.
According to the photographing system of the present invention, the exposure time appropriate for the quantity of light emitted from a sample can be calculated prior to actual photographing for acquiring an image signal, by performing temporary photographing in order to set exposure time for actual photographing. Thus, there is no need to perform photographing by trail and error as in the prior art. Furthermore, exposure time for the temporary photographing can be switched in accordance with a photographing method corresponding to the kind of sample to be photographed and/or the kind of light emitted from the sample, so that an appropriate temporary-photographing exposure time can be selected in accordance with a photographing method, particularly the quantity of light which varies depending on the kind of light emitted from a sample.
That is, in the photographing system of the present invention, a photographing method is input to the photographing-method input means. Then, the temporary exposure time setting means obtains a temporary-photographing exposure time corresponding to the input photographing method by making reference to the look-up table. The obtained temporary-photographing exposure time is input to the camera controller, which in turn controls the photoelectric read means so that the photoelectric read means is exposed in accordance with the input temporary-photographing exposure time, thereby performing temporary photographing. Based on an image signal (temporary-photographing image signal) photographed with the photoelectric read means by this temporary photographing, the actual exposure time setting means sets actual-photographing exposure time. The camera controller controls the photoelectric read means so that the photoelectric read means is exposed in accordance with the set actual-photographing exposure time, thereby performing actual photographing for acquiring an image analyzing signal.
According to the photographing system of the present invention, as described above, a sample can be photographed in an exposure time appropriate for the sample without relying on experience. In addition, by adding only the above-mentioned construction to a conventional photographing system, the photographing system of the present invention capable of easily obtaining this effect can be constructed. Thus, the present invention is excellent in upgrade performance.
The above and many other objects, features and advantages of the present invention will become manifest to those skilled in the art upon making reference to the following detailed description and accompanying drawings in which preferred embodiments incorporating the principle of the present invention are shown by way of illustrative example.